client.py

"""
Claude SDK Client Configuration
===============================

Functions for creating and configuring the Claude Agent SDK client.
"""

import json
import os
from pathlib import Path

from claude_code_sdk import ClaudeCodeOptions, ClaudeSDKClient
from claude_code_sdk.types import HookMatcher

from security import bash_security_hook


# Puppeteer MCP tools for browser automation
PUPPETEER_TOOLS = [
    "mcp__puppeteer__puppeteer_navigate",
    "mcp__puppeteer__puppeteer_screenshot",
    "mcp__puppeteer__puppeteer_click",
    "mcp__puppeteer__puppeteer_fill",
    "mcp__puppeteer__puppeteer_select",
    "mcp__puppeteer__puppeteer_hover",
    "mcp__puppeteer__puppeteer_evaluate",
]

# Built-in tools
BUILTIN_TOOLS = [
    "Read",
    "Write",
    "Edit",
    "Glob",
    "Grep",
    "Bash",
]


def create_client(project_dir: Path, model: str) -> ClaudeSDKClient:
    """
    Create a Claude Agent SDK client with multi-layered security.

    Security layers:
    1. Sandbox - OS-level bash command isolation
    2. Permissions - File operations restricted to project_dir only
    3. Security hooks - Bash commands validated against an allowlist
    """
    api_key = os.environ.get("ANTHROPIC_API_KEY")
    if not api_key:
        raise ValueError(
            "ANTHROPIC_API_KEY environment variable not set.\n"
            "Get your API key from: https://console.anthropic.com/"
        )

    security_settings = {
        "sandbox": {"enabled": True, "autoAllowBashIfSandboxed": True},
        "permissions": {
            "defaultMode": "acceptEdits",
            "allow": [
                "Read(./**)",
                "Write(./**)",
                "Edit(./**)",
                "Glob(./**)",
                "Grep(./**)",
                "Bash(*)",
                *PUPPETEER_TOOLS,
            ],
        },
    }

    project_dir.mkdir(parents=True, exist_ok=True)
    settings_file = project_dir / ".claude_settings.json"
    with open(settings_file, "w") as f:
        json.dump(security_settings, f, indent=2)

    print(f"Created security settings at {settings_file}")
    print(" - Sandbox enabled (OS-level bash isolation)")
    print(f" - Filesystem restricted to: {project_dir.resolve()}")
    print(" - Bash commands restricted to allowlist (see security.py)")
    print(" - MCP servers: puppeteer (browser automation)")
    print()

    return ClaudeSDKClient(
        options=ClaudeCodeOptions(
            model=model,
            system_prompt="You are an expert full-stack developer building a production-quality web application.",
            allowed_tools=[
                *BUILTIN_TOOLS,
                *PUPPETEER_TOOLS,
            ],
            mcp_servers={
                "puppeteer": {"command": "npx", "args": ["puppeteer-mcp-server"]}
            },
            hooks={
                "PreToolUse": [
                    HookMatcher(matcher="Bash", hooks=[bash_security_hook]),
                ],
            },
            max_turns=1000,
            cwd=str(project_dir.resolve()),
            settings=str(settings_file.resolve()),
        )
    )